1. Field of the Invention
The present invention relates to a personal identification device and a personal identification method which identify a person by using an identification element for identifying a person, such as a person's face image or voice. The present invention also relates to an updating method for identification dictionary data in a personal identification device, and an updating program for identification dictionary data which is used in a personal identification device.
2. Description of the Related Art
For example, there is known a personal identification method in which feature data of an identification element, such as the face, voice, or fingerprint of each of a plurality of persons to be identified, is stored as dictionary data in advance, and feature data of the above-mentioned identification element captured from a person to be identified is compared against the feature data of the identification element stored as dictionary data to thereby identify whose identification element the captured identification element of a person is.
According to this personal identification method, with a face image taken as an example of identification element, the above-mentioned face image of a person to be identified is captured, and dictionary data is generated by using feature data extracted from the captured face image. In this case, in order to average out errors in capturing in terms of the imaging conditions or face orientation at the time of capturing a face image serving as an identification element, it is common to capture a plurality of face images for the same person, and store averaged feature data as dictionary data for identifying that person (see Japanese Unexamined Patent Application Publication NO. 2003-271958).
Normally, when face image identification is performed anew for each individual person, the feature data of the face image of the person thus identified is reflected in identification dictionary data, thereby updating dictionary data of face image of each individual person.
In this case, according to the related art, dictionary data is generated and updated assuming that all captured face images have equal weight. That is, according to the related art, feature data of previously captured face images and newly captured feature data are all equally averaged in updating identification dictionary data. For example, newly captured feature data is added to identification dictionary data, and the added result is divided by the total number of times feature data has been captured to thereby calculate a simple average, and the thus averaged feature data is used as new identification dictionary data.